The difficulty in separating oil or oil-like products from oily liquids has generated several approaches to solve the problem. The problem is particularly troublesome with respect to removal of oil spills from water, especially turbulent water. One approach is to employ skimming devices and processes. One problem with this method as that water is often skimmed off with the separated oil, thereby necessitating further treatment.
Another method of separating the oil from the water is through the use of a sorbent. There are two types of sorbent materials, absorbents and adsorbents. Absorbents soak up oil whereas adsorbents provide a surface for the oil particles to cling to.
Sorbents may be divided into three general classes: (1) natural products, (2) modified or chemically treated natural products, and (3) synthetic or man-made products. U.S. patent to Sohl U.S. Pat. No. Re. 31,087 discloses a fibrous web which comprises a plurality of entangled oleophilic fibers. The fibers are hydrophobic in the presence of oil. The web comprises a plastic, such as nylon or polypropylene, having a large number of interconnected, interstitial spaces for reception and retention of oil to the exclusion of water.
Sorbents of a natural origin may be derived from a mineral source, which may include various clays and other micas and perlite and mixtures thereof. Examples of such sorbents are disclosed in the U.S. patents to Preus U.S. Pat. No. 4,111,813 and Weiler U.S. Pat. No. 3,527,701.
Other sorbents of a natural origin may be derived from vegetative sources, such as bark, as disclosed in the U.S. patent to Fahlvik U.S. Pat. No. 3,617,565. Wood pulp which has been chemically treated is disclosed as a sorbent in the U.S. patent to Field et al U.S. Pat. No. 4,343,680. A fibrous sorbent material, such as hemp, is disclosed in the U.S. patent to Armaly U.S. Pat. No. 2,399,158.
Some sorbents of a natural origin are derived from animal sources as disclosed in the U.S. patent to Schwartzwalder et al U.S. Pat. No. 3,219,194 (i.e. wood) and in the book "Oil Spill Prevention and Removal Handbook", pages 392 through 393, (i.e. feathers) published by the Noyes Data Corporation in 1974.
The use of such sorbent materials by themselves, however, have failed to provide a workable system in removing oil from water. Also, there are relatively high labor costs associated with the acquisition, transportation, stockpiling, deployment, distribution on and working into an oil slick, as well as retrieval and ultimate disposal thereof. Furthermore, such sorbent materials are typically only manually retrievable and only then under calm water conditions. Such products also interfere with equipment which physically removes the oil by clogging such skimming and suction devices. Such sorbent materials may also present a pollution problem on disposal. Many of such sorbent materials also ultimately sink, thereby limiting their usefulness.
Other prior art patents which are generally concerned with the problems addressed by the present invention include the U.S. patents to Jakubek U.S. Pat. No. 3,836,000, Grutsch et al U.S. Pat. No. 3,608,727 and Hiler U.S. Pat. No. 2,768,913.